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. .
.
..
,
..
.
%.
VALI DATI ON NOTI CE1
23 Mar ch 1990
ANSI / ASME B1. 2- 1983
16
May 1983
ANST/ ASME Bl . 2- 1983, adopt ed on 25 Oct ober 1984, has been r evi ewednd determ ned
t o be cur r ent .
Cust odi ans:
Ar my
-
AR
Navy - AS
Ai r Force
-11
Revi ew Act i vi t i es:
.r. Ar my - AT, AV, GL,
ME
User Act i vi t y:
Navy - EC
Ci vi l Agency Coor di nat i ng Act i vi t i es:
Commer ce - NI ST
DOT - ACO, APM, FAA, FRA, NHT
GSA
-
FSS, PLD
HUD
-
HSRS
J us t i ce - FPI
NASA
-
J FK, LRC, MSF
USDA - AFS
Pr epar i ng Act i vi t y:
DLA
-
IS
AREA THDS
DI STRI BUTI ON STATEMENTA. Appr oved f or publ i c r el ease; di st r i but i on
s
unl i m ted.
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Errata
to
ANSI/ASME Bl.2-1983
The Errata correction listed belowapplies
to
ANSI/ASME
B1.2-1983,
Gages and Gaging
for Unified Inch Screw Threads.
Page
Location Change
87 Table 11
Under
column 8, change thirdntry
from
.3744
o
.3739
MAY 1992
THE AMERICAN SOCIETY
OF
MECHANICAL
ENGINEERS
345 East 47th Street, New York, N.Y.
10017
N0058E
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A N
ASME B L - 2
8 3
A M E R I C A N
2 5 7 5 5 3 2
0 0 3 3 b 5 1
43 - b
N A T I O N A L
S T A N D A R D
Gages and Gaging for
Unified Inch Screw Threads
ANSI/ASME B1.2-1983
( R E V I S I O N OF AN SI B1.2-1974)
S PONSOREDA N DP U B L I S H E DB Y
T H E M E R I C A N O C I E T Y OF M E C H A N I C A L N G I N E E R S
U n i t e d n g i n e e r i n g e n t e r 3 4 5 East 4 7 t h t r e e t e w o r k , N. Y. 1 001
7
7
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This Standard wi ll be revised when the Society approves the issuance
of
a
new edition. There will
be no addenda o r written interpretations
of
the requirementsof this Standard issued to this Edition.
Date of Issuance: June
15,
1984
This code or standard was developed under procedures accredited
s
meeting the criteria for Ameri-
can National Standards. The Consensus Committee that approved the code or standard was balanced
to assure that individuals from competent and concerned interests have had an pportunity to partici-
pate. The proposed code or standard was made available for publ ic review and comment which pro-
vides an opportunity for additional public inpu t from industry, academia, regulatory agencies, and in
the public-at-large.
ASMEdoes not "approve," rate,"or endorse"any tem, construct ion, proprietary device, or
activity.
ASME does not take any position with respect to the valid ity of any patent rights asserted in con-
nection with any items mentioned in this document, and does not undertake o insure anyone utili zing
a standard against liability for infringement
of
any applicable Letters Patent, nor assume any such
lia-
bili ty. Users of a code or standard are expressly advised that determination of the validity of any such
patent rights, and the risk
of
infringement of such rights,
is
entirely their own responsibility.
Partic ipation by federal agency representative(s) or person(s) affiliated with industry
is
not to be in-
terpreted
as
government or ndustry endorsementof this code or standard.
ASME does not accept any responsibil ity for interpretations of this document made by individual
volunteers.
No part of this document may be reproduced in any form,
in an electronic retrievalsystem or otherwise,
without
the
prior written permissionof the publisher,
Copyright
0
1984 by
THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
Al l Rights Resewed
Printed in U.S.A.
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ASME B I - 2 8 3 2 5 7 5 5 1 2 OOll1653 2
FOREWORD
(This Foreword is no t part
of
Amer ican Nat iona l S tandard ANSVA SME 61.2-1983,
Gages and Gaging for Un i f ied Inch Screw Threads.)
American National Standards Committee B1 for the Standardization of screw threads
was organized in 1920 as Sectional Committee B1 under the aegis of the American Engi-
neering Standards Committee (later the American National Standards Association, then
the United States of America Standards Institute and,as of.October 6, 1969, the American
National Standards Institute, Inc.), with the Society of Automotive Engineers and the
American Society of Mechanical Engineers as. oint sponsors.
In 1982, American National Standards Committee B1 was reorganized as the ASME
Standards Committee BI, and since then it has operated under the American Society of
Mechanical Engineers Procedures t o produce and update standards which may become
ANSI Standards after final approval by the American National Standards Institute.
A declaration
of
accord with respect to the unification of screw threads was signed on
November 18, 1948, by representatives of the services and industry of the United States,
the United Kingdom, and Canada.The ANSI Unified Screw Thread Standard BI., through
the quadripartite standardization greement (QST AG) 247, Unified Threads, is subject to
an international standardization agreement through the instrumentality of the American-
British-Canadian-Australian Army Standardization Program, which recognizes BI.
I
as
a standard forUnified Threads when it is required to effect the interchangeability of parts
and equipment between the armies of the participating nations.
The first American National Standard for Screw Thread Gages and Gaging was pub-
lished as ASA B1.2-1941 to supplement the parent Standard SA B1.l-1935, ScrewThreads
for Bolts, Nuts, Machine Screws and Threaded Parts. That Standard was revised and re-
published as a Unified Standard ASA Bl.1-1949 and again as ASA Bl.1-1960. The Uni-
fied Gage Standard was republished as ASA B1.2-1951 and USA B1.2-1966.
On February 9, 1973, a meeting was held by the Department of Commerce at the Na-
tional Bureau of Standards, Washington, D.C., attended by representatives of government
and industry screw thread interests. With the goal of eliminating parallel‘standards, those
at the meeting recommended that theNBS Handbook H-28 be converted into a coordinat-
ing document for government screw thread standards wherein sections of H-28 would be
replaced by single page references to existing industry standards. It was further recom-
mended that the chairmanof American National Standards Committee B1 set up a group
to clearly define and establish identified levels of acceptability for screw threads.
At an American National Standards Committee 1 meeting held on May 3, 1973, unani-
mous approval was given to t he following motion: “The BI Committee recognizing the
needs of industry for different levels of acceptability for screw threads, establishes new
scopes for StandardsB 1.1 and B 1.2 and sets up a new standard, B1.3.” References to con-
formance criteria were removed from ANSI B1.2-1974 and additional gages and gaging
data were added to suit additional conformance requirements specified in ANSI B1.3 or
other B1 thread documents.
This new publication, designated ANSIIASME B1.2-1983, has had considerable new
material added to cover the many options of gages and measuring equipment shown in
ANSI B1.3, Screw Thread Gaging Systems for Dimensional Acceptability. I t has also re-
...
111
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ASME B 3 - 2 83
2 5 7 5 5 3 2 OOL365q
L
applied HI and
LO
to function as NOT
GO
gages and has eliminated gages with pitch di-
ameter outside product thread limits. ANSI B1.2 was approved by the ASME Standards
Committee B1 on March 18, 1983.
The proposed standard was submitted by the ASME Board of Standardization to the
American NationalStandardsInstitute. It was approved and formally designated an
American National Standard
on
May
16, 1983.
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ASMESTANDARDSCOMMITTEE
B I
Standardization and Unification
of
Screw Threads
(The fol lowing is the roster f the Commi t tee a t the t ime o f approva l o f th is S tandard.)
OFFICERS
D. J. Emanuell i , Chairman H.
W.
Ell ison, Vicehairman
C. E. Lynch,
Secretary
COMMITTEE
P E RS O NNE L
AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC.
G. G . Gerber, McDonnel l Douglas, St. Louis, M issouri
H. Borrman, Alternate, Sperry Gyroscope Division, Grea t Neck, Ne w York
AMERICAN IRON AND STEEL INSTITUTE
F.
Dallas,
Jr.,
Saw hil l Tu bular Division, Sharon, P ennsylvania
AMERICAN MEASURING TOO L MANUFACTURERS ASSOCIATION
D.
Dodge, Pennoyer-Dodge Company, Glendale, California
C .
W.
Jatho,
Alternate,
Ame rican Measu ring Tool Manufacturers Association, Bi rmingham, Michigan
AMERICAN PIPE FllT lNG S ASSOCIATION
W. C. Farrell , Stockham Valves and Fittings, Birmingham, Alabama
DEFENSE INDUS TRIAL SUPPLY CENTER
E. Schw artz, Defense Industria l Supp ly Center, Philadelphia, P ennsylvania
F. S.
Ciccarone,
Alternate,
Defen se Industrial Supply Center, Philadelphia, Pennsylvania
ENGINE MANUFACTURER S ASSOCIATION
G.. A. Russ, Cum mins Engine Company, Columbus, Indiana
FARM AND INDUSTRIAL EQUIPMENT INSTITUTE
J. F. Nagy, Ford.Motor Company, Dearborn, Mich igan
INDUST RIAL FASTENERS INSTITUTE
R .
B . Belford , Indus trial Fasten ers Institute, Cleveland, Ohio
R. M.
Harris, Bethlehem Steel Company, Lebanon, Pennsylvania
K . E. Mc Cullo ugh , SPS Technologies, Inc., Je nkintown, Pennsylvania
J.
C. Mc Mu rray , Russel l, Burd sal l and Wa rd nc., Mentor, Ohio
J. A.
Tri l l ing, Holo-Krome Company, We st Hartford, Connecticut
E. D. Spengler, Alternate, Bethlehem Steel Company, Lebanon, Pennsylvania
MANUFACTURERS STANDARDIZATION SOCIETY OF THE VALVE AND FllTlNG INDUSTRY
W. C. Farrel l , Stockham Valves and Fitting, Birmingham, Alabama
MET AL CUTTING TOOL INSTITUTE (TAP AND DIE DIVISION)
N. F. Nau, Union/Butterf ie ld, Athol , Massachusetts
A.D. Shepherd, Jr., Alternate, Union/Butterf ie ld, Derby Line, Vermon t
NATIO NAL AUTOMATIC SPRINKLER AND FIRE CONTROL ASSOCIATION, INC.
W.
Testa, Grinne ll Fire Protec tion System s Company, Inc., Providence, Rhode Island
R .
P. Fleming,
Alternate,
Nationa l Automa tic Sprinkler and Fire Co ntrol Asso ciation, nc., Patterson, N ew York
V
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A S M E
8 3 . 2
83
M
2 5 9 5 5 3 2 0 0 1 3 6 5 b
8 M
NATIO NAL ELECTRICAL MANUFACTURERS ASSOCIATION
J.
L. Gri ff in, W heatland Tube Company, Wheatland, Pennsylvania
J. B. Levy, G eneral Electric Company, Schenectady, N ew York
F. F. Weingruber, Westinghouse Electric Corp., Pittsburgh, Pennsylvania
W .
R .
Wi l l i fo rd ,
Alternate
National Electr ical M anufacturers Association, W ashington, D.C.
NATIONAL MACHINETOOL BUILDERS ASSOCIATION
R .
J.
Sabatos, The Cleveland Twist Dri l l Company, Cleveland, Ohio
D.
R .
Stoner, Jr., Teledyne Landis Mach ine, Wayneshoro, Pennsylvania
NATIONAL SCREW M ACHIN E PRODUCTS ASSOCIATION
T. S . Meyer, Fischer Spe cial Manuf actu ring Company, Cold Spring, Kentucky
H.
A . Eichstaedt, Alternate Nationa l Screw Ma chine Produc ts Association, Brecksvil le, Ohio
SOCIETY OF AUTOMOTIVE ENGINEERS
H. W. El l ison, General Motors Technical Center, Warren. M ichigan
SOCIETY OF MANUFACTURING ENGINEERS
D.
Davidson, Morse/Hem co Corporation, Holland, Michiga n
TUBULAR RIVET AND MACHINE INSTITUTE
R . M. Byrne, Indus try Service Bureaus, Inc., Wh ite Plains, New York
U.S. DEPARTMENT OF THE AIR FORCE
R . P. Stewart, Wright-Patterson, Ohio
U S . DEPARTMENT OF THE ARM Y
F. J. Clas, U S . Department of the Army, W atervliet, N ew York
J.
C rowl ey , U S . A rm y Ma te r i a lDevelopment and Readiness Command, Alexandria, Virginia
F.
L. Jones, Alternate U.S. Army Missle Command, Redstone Arsenal, Alabama
U S . DEPARTMENT OF DEFENSE
E. Schwartz, Defense Industrial Supply Center, Philadelphia, Pennsylvania
U. S. DEPARTMENT OF THE NAVY
C. T. G ustafson, Portsmouth Naval Shipyard, Portsmouth, New Hampshire
INDIVIDUAL MEMBERS
C. T. Appleton, Jefferson, Massachusetts
J.
Boehnlein, PMC Industr ies, Wickl i ffe, Ohio
R . Browning , Southern Gage Company, Erin, Tennessee
R . S. Cham erda, The Johnson Gage Company, Bloomfield, Connecticut
J. F.
Cramer, Des Moines, Washington
E. W. Dresc her, Lancaster, Pennsylvania
D.
J.
Emanuel l i , Greenfield Tap and Die, Greenfield, Massachusetts
C . G. Erickson, Colt Industries - ter l ing Die Operation, West H artford, Connecticut
S.
I. Kanter, P.E., The Hanson-Whitney Company, Hartford, Connecticut
R . W.
Lamp ort, Th e V an Keuren Company, Watertown, Massachusetts
A.
R .
Machel l ,
Jr,,
Xerox Corp., Rochester, Ne w York
A. E.
Masterson, Watervl iet, New York
R . E. Mazzara, Ge ometric Tool, Ne w Haven, Connecticut
P. V. Pastore, Regal Beloit Corp., So uth Beloit, Il l inois
M. M. Schu ster, Hi-She ar Corporation, Torrance, California
A.
G. Strang, Boyds, Maryland
A.
F.
Thibodeau, Swanson Tool Man ufacturing, lnc., We st Hartford, Connecticut
J.
W.
Turton, The Bendix Corp., Greenfield, Massachusetts
Subcommittee
B I .2
- Screw Thread Gages and Gaging
R .
Browning, Chairman Southern Gage Company, Erin, Tennessee
A. F. Thibodeau, Secretary Swanson Tool Manufacturing, Inc., West Hartford, Connecticut
P.
F.
Bitters, Greenfield Tap and Die, Greenfield, Massachusetts
J. Boehnlein, PMC Industr ies, Wickl i ffe, Ohio
vi
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D. Cadieux, Greenfield Tap and Die, Greenfield, Massachusetts
R .
S.
Chamerda, The Johnson Gage Company, Bloomfield, Connecticut
M.
Davidson, Morse/Hemco Corp.. Holland, Michigan
D. Dodge, Pennoyer-Dodge Company, Glendale, California
H. W. Ellison, General Motors Technical Center, Warren, Michigan
J.
J.
Fiscella, Latham, New York
G. Garcina, Indianapolis, Indiana
C. T. Gustafson, Metrology Laboratories Division, Portsmouth, New Hampshire
S.
1. Kanter, The Hanson-Whitney Company, Hartford, Connecticut
R .
W.
Larnport, The Van KeurenCompany, Watertown, Massachusetts
A.
E.
Masterson, Watervliet, New York
K. E. McCullough, SPS Technologies, Inc., Jenkintown, Pennsylvania
J.
C. McMurray , Russell, Burdsall and Ward, Inc., Mentor, Ohio
J.
Preziosi, Amerace-Esna Corp., Union, New Jersey
M. M.
Schuster, Hi-Shear Corp., Torrance, Califo rnia
E.
Schwarfz, Defense Industrial Supply Center, Philadelphia, Pennsylvania
A. G. Strang, Boyds, Maryland
J. W. Turton, The Bendix Corp., Greenfield, Massachusetts
A. Zaverucha, McM ellon Brothers, Stratford, Connecticut
Task Group
B I.I -
Gages and Gaging
for
Metric
M
Screw Threads
C.
G.
Erickson,
Chairman,
West Hartford, Connecticut
R .
Browning,
Secretary,
Southern Gage Company, Erin, Tennessee
R.
S.
Charnerda, The. Johnson Gage Company, Bloomfield, Connecticut
M. Davidson, H. E. Morse Company, Holland, Mich igan
D. Ernanuelli , Greenfield Tap and Die, Greenfield, Massachusetts
S.
1. Kanter, The Hanson-Whitney Company, Hartford, Connecticut
R .
W. Lamport, The Van Keuren Company, Watertown, Massachusetts
K. E. McCullough, SPS Technologies, Inc., Jenkintown, Pennsylvania
J.
C. McMurray, Russell, Burdsall, and Ward, Inc., Mentor, Ohio
E.
Schwartz, Defense Industrial Supply Center, Philadelphia, Pennsylvania
A.
G. Strang, Boyds, Maryland
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A S M E B I - 2 83 m
2 5 7 5 5 3 2
0033658
3
m
CONTENTS
...
Foreword ........................................................................
111
Standards Committee Roster
.......................................................
V
1
Introduction
................................................................ 1
1.1 References
.............................................................
1
1.2 Classification ........................................................... 1
1.3 Federal Government Use ................................................. 1
2
Basic Principles
............................................
;
. . . . . . . . . . . . . . . .
1
2.1 Accuracy in Gaging ..................................................... 1
2.2 Limitations of Gaging
................................................... 1
2.3 Determining Size of Gages
...............................................
10
2.4 Standardemperature ................................................... 10
3 General Practice ............................................................
10
3.1 General Design ......................................................... 10
3.2 Types
of
Gages ......................................................... 10
3.3 Interpretation of Tolerances
..............................................
10
3.4 Direction of Tolerances on Gages
.......................................... 10
3.5
Standardhread Gage Tolerances ......................................... 11
3.7 Tolerances on Half-Angle
................................................
11
3.8 Check of Effect of Lead andFlank Angle Variations onProduct Thread
.......
11
3.9 Calibration Requirements andtandards
...................................
11
3.6 Tolerance on Lead
......................................................
11
4 Types of Gages for Product InternalThread ..................................
4.1 GO Working ThreadPlug Gages
..........................................
4.2 NOTGO (HI) ThreadPlug Gages
.........................................
4.3 Thread Snap Gages
-
O Segments or Rolls
..............................
4.4 Thread Snap Gages
-
OT GO (HI) Segments or Rolls .....................
4.5 Thread Snap Gages Minimum Matehal: Pitch Diameter Cone and
4.6 Thread Snap Gages
-
Minimum Material: Thread Groove Diameter
Vee ..................................................................
Type
................................................................
4.7 Thread-Setting Solid Ring Gages
..........................................
4.9 Snap and Indicating Gages to Check Major Diameter of Internal Thread
.......
4.10 Functional Indicating Thread Gages for Internal Thread
......................
4.11 Minimum-Material Indicating Thread Gages for Internal Thread
...............
4.12 Indicating Runout Thread Gage for Internal Thread
.........................
4.13 Differential Gaging
......................................................
4.8 Plain Plug. Snap. and Indicating Gages to Check Minor Diameter of
InternalThread .......................................................
11
11
13
14
20
20
23
24
24
28
28
33
33
37
ix
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4.14 Pitch Micrometers ...................................................... 39
4.15 Thread-M.easuring Balls
..................................................
39
4.16 OpticalComparatornd Toolmaker’s Microscope
...........................
39
4.17 Profileracingnstrument
...............................................
40
4.18 Surface Roughness Equipment ............................................ 40
4.19 Roundnessquipment ................................................... 40
4.20 Miscellaneous Gages and Gaging Equipment ................................ 40
5 Types
of
Gages for Product External Thread
.................................. 40
5.1 GOWorkingThread Ring Gages
..........................................
40
5.2 NOT GO (LO) ThreadRing Gages
........................................
128
5.3 Thread Snap Gages O Segments or Rolls
..............................
129
5.4 Thread Snap Gages - OTGO (LO) Segments or Rolls .................... 131
5.5 ThreadSnap Gages one nd Vee
......................................
133
5.6 Thread Snap Gages -Minimum Material: Thread Groove Diameter Type
.....
133
5.7 Plain Ring and Snap Gages to Check Major Diameter of Product
ExternalThreads
......................................................
133
5.8 Snap Gages forMinor Diameter of ProductExternalThreads .................
135
5.9 Functional ndicatingThread Gages for ExternalThread ..................... 135
5.10 Mimimum-Material ndicatingThread Gages for ExternalThread
.............
139
5.12 Differential Gaging ...................................................... 139
5.13 WToleranceThread-Setting Plug Gages ................................... 143
5.14 Plain Check Plug Gages for Thread Ring Gages
.............................
148
ExternalThreads
......................................................
148
5.16 Indicating Gages to Check MinorDiameter
of
ExternalThread
...............
148
5.17 Thread Micrometers .................................................... 159
5.18 Thread-Measuring Wires
.................................................
159
5.19 Optical Comparator nd Toolmaker’s Microscope
...........................
159
5.20 Profile Tracingnstrument
...............................................
160
5.21 Electromechanical Lead Tester ............................................ 160
5.22 Helical Path Attachment Used With GO Type Thread Indicating Gage
.........
160
5.23 Helical Path Analyzer
...................................................
160
5.24 Surface Roughness Equipment
............................................
161
5.25 Roundness Equipment
...................................................
161
5.26 Miscellaneous Gages andGagingEquipment
................................
161
5.11 IndicatingRunout Gage forExternalThreads
..............................
139
‘5.15 Indicating Plain Diameter Gages-Major Diameter
of
Product
Figures
1Maximum-MaterialGOFunctional Limit
.........................................
12
2PartialEndThreadsand Chip Grooves
...........................................
14
3
NOTGO HI) FunctionalDiameter Limit
........................................
16
4ThreadSnap Gages -Maximum-Material GO Functional Limit ................... 19
5Thread Snap Gages- OT GO HI)FunctionalDiameter Limit
...................
21
6 Thread Snap Gages
-
Minimum-Material Pitch Diameter Limit
-
one and Vee
. . . . .
22
7Thread Snap Gages Minimum-Material Thread Groove Diameter Limit
...........
23
8Thread Form of Solid Thread-Setting Ring Gages .................................. 26
9MinorDiameter Limit
-
ylindrical Plug Gages
..................................
27
10 Indicating Plain Diameter Gages-Max.-Min. Minor Diameter Limit
11 Snap and Indicating Diameter Gages
-
Max.-Min. Major Diameter
and Size ................................................................... 29
Limit and Size
..............................................................
30
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A S M E
BL.2
83 W
2595512 O O l l b b O T
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Indicating Thread Gages.aximum-Material GO Functional Limit and Size ......
Indicating Thread Gages.inimum-Material Pitch Diameter Limit and
Size.one and Vee .......................................................
Indicating Thread Gages.inimum-Material Pitch Diameter Limit
and Size-BallandR adius .................................................
Indicating Thread Gages
-
iameter Runout
-
Minor to Pitch
.....................
Indicating Thread Gages- ifferentlal Gaging ........: .........................
Inside Micrometer, Caliper Type
................................................
Maximum..M aterial GO Functional Limit
........................................
NOT GO (LO) Functional Diameter Limit .......................................
Thread Snap Gages
-
Maximum-Material GO Functional Limit ...................
Thread Snap Gages
-
OT GO (LO) Functional Diameter Limit ...................
Thread Snap Gages
-
Minimum-Material Pitch Diameter Limit one and Vee
.....
Thread Snap Gages
-
Minimum-Material Thread Groove Diameter Limit
...........
Major Diameter Limit
.........................................................
Minor Diameter Limit Snap Type
................................................
and Size ...................................................................
andsize-ConeandVee ....................................................
Limit and Size
..............................................................
Indicating Thread Gages-Maximum-Material GO Functional Diameter Limit
Indicating Thread Gages
-
Minimum-Material Pitch Diameter Limit
Indicating Thread Gages Minimum-Material Thread Groove Diameter
Indicating Thread Gages- iameter Runout-Major to Pitch
.....................
Indicating Thread Gages- ifferential Gaging
...................................
Thread Form of Truncated Thread-Setting Plug Gages
.............................
Thread Form of Full-Form Thread-Setting Plug Gages
............................
Indicating Plain Diameter Gage
-
Max.-Min. Major Diameter Limit and Size ........
Indicating Diameter Gages-Max.-Min. Minor Diameter Limit and Size
............
Indicating Gage ..............................................................
ndicating Gages- elical Pa th Attachment Used With GO Type
31
34
35
36
38
39
127
129
130
132
134
135
136
137
138
140
141
142
144
146
147
149
150
160
Tables
1 Screw Thread Gages and Measuring Equipment for External Product
2 Screw Thread Gages and Measuring Equipment for Internal Product
Thread Characteristics ......................................................
2
Thread Characteristics ......................................................
6
3 Recommended Widths for Chip Grooves ........................................ 13
ThreadedandPlain Gages for Unified Externaland nternalThreads ............. 15
Setting Gages for Unified Thread Working Gages .............................. 17
6 X Gage Tolerances forThread Gages
............................................
18
7W Gage Tolerances forThread Gages
...........................................
25
9Constants orComputingThread Gage Dimensions
...............................
32
Screw Threads - imits of Size ............................................. 41
and 3B UnifiedScrew Threads- imits of Size ............................... 83
4 Specifications and Format for Tables 10 and 11- imits of Su e of
5
Specifications and Format for Tables 10 and 11- imits of Size
of
Thread-
8
Gage Tolerances for Plain Cylindrical Gages .....................................
28
10
Gages for Standard Thread Series. Classes 1A. 2A. 3A. 1B. 2B. and 3B Unified
11 Setting Gages for Standard Thread Series. Classes 1A. 2A. 3A. 1B. 2B.
12 Calibration Requirements and Standards for X Tolerance Thread Gages.
Indicating Gages. Plain Gages. and Measuring Equipment for External
ProductThreads ............................................................ 151
xi
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13 Calibration Requirements and Standards for
X
Tolerance Thread Gages.
Indicating Gages. Plain Gages. and Measuring Equipment for Internal
Producthreads
...........................................................
155
14 Calibration Requirements for Thread-andPlain-Setting Gages ..................... 159
Appendices
A Calibration and Inspection of Limit Gages. Snap Gages. Indicating Gages.
and Measuring Instruments
Al General
................................................................
163
A2 Threadlug Gage Calibration ............................................ 163
A3 ThreadRing Gage Inspection ............................................ 164
A4 Plainlug Gage Calibration
.............................................
167
A5 PlainRing Gage Calibration ............................................. 168
A6 Plainnap Gages ....................................................... 168
A7 Rolls With Zero Lead Thread Form Used on Snap and Indicating
Gages
...............................................................
168
A8 Inspecting PeripheralContacting Segments Used on External
ProductThread
......................................................
168
A9 Inspection
of
ThreadContact Segments Used on
InternalProductThread ............................................... 170
A10 Check for Magnification Discrepancies Due to Indicating
System Linkage
......................................................
170
Al
1
Calibration of Dial nd Electronic Indicators .............................. 170
A12 Assessment of Surface Quality
...........................................
171
B
Metrology
of 60
deg
.
Screw Threads
........................................ 173
B1 Wire Method of Measurement of Pitch Diameter (Thread Groove
Diameter)
.....................................
i ...................... 173
B2 Size of Wires
...........................................................
173
B4 Methods of Measurement UsingWires
....................................
176
B5 Standard Specification for Wires and StandardPractice in Measurement
of Wires of60 deg Threads
............................................
176
B6 General Formula or Measurement of Pitch Diameter
.......................
177
B7 Simplified Formula for Pitch Diameter
....................................
177
B8 Setting Measuring Instruments With Variable Measuring Force . . . . . . . . . . . . . . . 178
B9 Thread Balls ........................................................... 178
B10 Internal itch Diameter Measurement
.....................................
179
B3 Methods of Measuring Wires Considering the Effect of Deformation . . . . . . . . . . 173
Figure
B1 A Three-Wire Method of Measuring Pitch (Thread Groove)
Diameter of ThreadPlug Gages ............................................. 174
Tables
Al
Minimum
Magnification ....................................................... 164
A2 60 deg. Included Thread Angle
.................................................
165
A3 Lengths of AGD Taperlock and Trilock Thread Plug Gage Blanks
A4 Lengths of AGD Thread Ring Gage Blanks and Total Thread Lengths
Selected FromANSI B47.1
..................................................
166
of Standard Truncated-Setting Plug Gage Blanks Selected from ANSI
B47.1 ..................................................................... 169
B1 Thread-Measuring Wires for 60 deg Screw Threads .............................. 175
and Wire Calibration. and Cylindrical Diameter for Wire Calibration
. . . . . . . . . . . . . . . . . . . .
176
Measurementnd Ball Calibration
...........................................
179
B2 Measuring Force for Over-Wire Measurements of External Pitch Diameter
B3 Measuring Force Over Balls for Internal Pitch Diameter
xii
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ANSI/ASME
61.2-1983
A NAMERICANNATIONAL STANDARD
AN AMERICAN NATIONAL TANDARD
GAGES AND GA GING FOR UNIFIED INCH SCREW THREADS
1 INTRODUCTION
This Standard provides essential specifications and
dimensions for the gages used on Unified inch screw
threads (UN and UNR thread form), and covers the
specifications and dimensions for the thread gages
and measuring equipment listed in Tables 1 and . The
basic purpose and use of each gage are also described.
1,I References
The latest editions of the following documents form
a part
of
this Standard, to he extentspecified herein.
American National Standards
ANSI B1.l
ANSI B1.3
ANSI B1.7
ANSI B46.1
ANSI B47.1
ANSI B89.1.6
ANSI B89.1.9
ANSI B89.3.1
Unified Inch Screw Threads (UN
and UNR Thread Form
Screw Thread Gaging Systems for
Dimensional Acceptability
Nomenclature, Definitions, and
Letter Symbols for Screw Threads
Surface Texture: Surface Rough-
ness, Waviness, and Lay
Gage Blanks
Measurement of Qualified Plain
Internal Diameters for Use
as
Master Rings and Ring Gages
Precision Inch Gage Blocks for
Length Measurement (Through 20
in.)
Measurement of Out-of-Round-
ness
for Federal Services, Section 6, the use of this Stan-
dard by the federal governmentwill
be
subject to all re-
quirements and limitations of FED-STD-H28/6.
2 BASIC PRINCIPLES
2.1 Accuracy n Gaging
Thread plug gages are controlled by direct measur-
ing methods. Thread ring gages, thread snap limit
gages, and indicating thread gages are controlled by
reference to the appropriate setting gages or direct
measuring methods or both.
2.2 Limi tations of Gaging
2.2.1 Product threads accepted by a gage of one
type may be verified by other types. It is possible,
however, that parts which are near a limit may be ac-
cepted by one type and rejected by another. Also, it
is possible for two individual limit gages of the same
type
to
be at opposite extremes of the gage tolerances
permitted, and borderline product threads accepted
by one gage could be rejected by another. For these
reasons, a product screw thread is considered accep-
table when it passes a test by any of the permissible
gages in ANSI B1.3 for the gaging system specified,
provided the gages being used are within the toler-
ances specified in this Standard.
1.2 Classification
In this Standard, the term NOT GO, previously
known as H I and LO, is used to identify functional
diameter thread gages.
1.3 Federal Government Use
When this Standard is approved by the Depart-
ment of Defense and federal agencies and is incorpo-
rated into FED-STD-H28/6,Screw Thread Standard
I
2.2.2 Gaging large product external and internal
threads equal to or greater than 6.25
in.
nominal size
with plain and threaded plug and ring gages presents
problems for technical and economic reasons. In
these instances, verification-may be based on use of
modified snap or indicating gages or measurement of
thread elements. Various types of gages or measur-
ing devices in addition to those defined in this docu-
ment are available and acceptable when properly cor-
related to this Standard. Producer and user should
agree on the method and equipment used.
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A S M E B 1 . 2
83
M 2 5 7 5 5 1 2 0 0 1 1 b b 3 5
H
GAGES AND GAGING FOR
UNIFIED INCH SCREW THREADS
-
\
ANSVASME 61.2-1
983
AN AMERICAN NATIONAL STANDARD
TABLE
1
S CREW THRE A D GA GE S A ND ME A S URING E QUIP ME N T FOR
EXTERNAL PRODUCT THREAD CHARACTERISTICS
T
Unif ied Inch Threads
NOT
GO
Functional
Diam.
Maximum
Material
CO
I
-
-uric.
Limit
Func. Func.
Limit I
Size
hread Gages
and
Measuring Equipment
1 Split or Solid Threaded Rings (ANSI 847.1)
1.1 GO
1.2
NOT GO (LO)
e
2 Thread SnapGages
2.1 G O
segments
2.2 NOT
G O (LO)
segments
2.3
G O
rolls
2.4 N O T G O
(LO)
rolls
e
2.5 Minimum material
-
itch diameter type-cone and ee
2.6 M in im um material -th read groove diameter
type- one only
3 Plain Diameter Gages
3.1 Plain cylindrical ring for major diameter
3.2 Major diameter snap type
3.3 Mi no r diameter snap type
3.4 Maximum and minimum major diameternap type
3.5 Maximum and min imum minor diameter nap type
4
Indicating Thread Gages
Having either two contacts at 180 deg. or three contacts
a t 120 deg.
4.1 G O segments
e
e
e e
.3 G O rolls
e
4.5 Minimum
mater ia l -p i t chd iameter type-coneandvee
4.6 M in im um material- hread groove diameter type
- one only
4.7 Major diameter and pitch diameter runoutage
2
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GAGES AND GAGING FOR
UNIFIED INCH SCREWTHREADS
' ASME 8 1 . 2
83 W
2 5 7 5 5 1 2 0011664 7 =
A N S V A S M E 61.2-1983
. AN AMERICAN NATIONAL STANDARD
3
-7
Surface
Texture
N
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A S M E 81.2
8 3
2 5 7 5 5 3 2 0 0 1 L b b 5
9
ANSIIASME B1.2-1983
AN AMERICAN NATIONALSTANDARD
GAGES AND GAGING
FOR
UNIFIED
INCH
SCREW THREADS
TABLE
1
SCREW TH READ GAGES AND MEA SURING EQUIPMEN T FOR
EXTERNAL PRODUCT T HREA D CHA RAC TERISTICS (CONT'D)
T
Unified Inch Threads
T
Minimu m Material
aximum
Material
GO
NOT
GO
Functional
Diameter
T
hd. Groove
Diam.
itch Diam.
Func
Size
Func.
l im i t
Func.
Func.
limit Size
hread Gages
and
Measuring Equipment
l imit
C1
-
.8 D i f f e r en t i a l s egm en t o r roll
( G O
pr o f i l e f o r one p i t chn l ength) used in com binat ion
with a
G O
i nd i ca t i ng gage t o y i e l d a d i am e t e r equ i va l en t
for var iat ion in lead ( including uniformity of helix);
and a minimum mater i a l i ndicat ing gage to y i e ld a
diameter equivalent for var i a t ion n f l ank angle
5 ndicat ing Plain Diame terGages
5.1 Major d i ameter t ype
5 .2 M i no r d i am e t e r t ype
6 Pi tch Microme ter Wi th Standard Contact s Approxim ate ly
~ ~~~~~
NOT G O
(LO)
P ro fi le ] C on e a nd Vee
7
Pitch MicrometerWi thModi f i edContact s Approximate ly
P it ch D i am e t e r C on t ac t ] C one and V ee
8
Thread-Measur ing Wi res Wi th Sui t able Measur ing Means
e
e e
O pt i ca l C om par a t o r and T oo l m ake r ' s M i c r os cope W i t h
Sui table Fixtur ing
1 0 Profile Tracing Equipmen t With Sui table Fixtur ing
A
11
Lead Measur ingMachineWi thSui tableFixtur ing
1 2 Hel i cal Path At t achment Used Wi th GOType Indicat ing Gage
i
3HelicalPathAnalyzer
14 P la in M i c r om e t e r and C a l i pe r s
-
Modi f i ed As Requi r ed
15Sur faceM eas u r i ngE qu i pm en t
4
6
R oundnes squ i pm en t
I
L
NOTE:
(1) Maximum minor d i ameter l imi t is a c c e p t a b l e w h e n p r o d u c t p a s s e s G O g a g e on U N and UNR threads .
4
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- ` - `
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ASME
B L - 2
83
2 5 7 5 5 3 2 O O L l b b b 0
m
ANSVASME
B1.2-1983
AN AMERICANNATIONALSTANDARD
i<
F
3
.
- ~.~
~ _ _ _ _ _
GAGES AND GAGING FOR
UNIFIED NCHSCREWTHREADS
TABLE 1 SCREW T HREAD G AGES AN D MEASUR I NG EQ UI PMENT F O R
EXTERNAL PRODUCT THREAD CHARA CTERISTICS (CONT'D)
Roundness of
Pitch Cylinder
Taper
of Pitch
Cylinder
l ead
Incl. Flank
Helix Angle
Size Variation Variation
-_
Major
Diameter
Minor
Diameter
Diam.
Runout
Major
to Pitch
Size
Surface
Texture
N
Root
Rad.
L
l im i timit
I2
1
Size
e
e
e
K 1
M
e
e
5
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ANSVASME
61.2-1
983
AN AMERICAN NATIONAL STANDARD
GAGES AND GAGING
FOR
UNIFIED INCH SCREW THREADS
TABLE
2
S CREW THRE A D GA GES A ND M E A S U RING E QUIP ME NT F OR
INTERNAL PRODUCT THREAD CHARACTERISTICS
Thread Gages
and
Measuring Equipment
1
Threaded
Plugs
(ANSI 847.1)
1.1 GO
1.2 NOT
GO (HI)
2 Thread SnapGages
2.1
GO
segments
2.2 NOT G O (HI) segments
2.3
GO
rolls
2.4 NOT
GO (HI)
rolls
2.5 Mi ni mu m material
-
itch diameter type - one
and vee
2.6 Mi ni mu m material
-
hread groove diameter type
-
one only
3 Plain Diameter Gages
3.1
Plain cylindrical plugs for mino r diameter
3.2 Ma jo r diameter snap type
3.3 Mi no r diameter snap type
3.4 Maximu m and minimum major diamet er snap type
3.5 Maximu m and minimu m minor diamete r snap type
4
indicating Thread Gages
Having either tw o contacts at 180 deg or three
contacts at 120 deg.
4.1
GO
segments
4.3
GO
rolls
Unified Inch Threads
Material
NOT
GO
Functional
Diameter
T
Minimum Material
Pitch Diam.
6
l imit Size
C1 C2
Thd. Groove
Diam.
l i m i t
D2
1
Size
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A S M E B 3 . 2 3 W 2 5 7 5 5 3 2Ö O L l b b 8 4 W
GAGESANDGAGING FOR
UNIFIED NCHSCREWTHREADS
A N S V A S M E
61.2-1983
ANAMERICANNATIONALSTANDARD
TABLE 2 SCREW THREA D GAGES A N D MEASU-RING EQUIPMENT FOR
INTERNAL PRODUCT THREAD CHA RACTERISTICS (CONT'D)
Major
Diameter
f
imitize
[Note1)
-"-
Note
I )
~
Note
1)
iNote I
I--
(Note 1
7
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ANSI/ASME
61.2-1
983
AN AMERICAN NATIONAL STANDARD
GAGES AND GAGING FOR
UNIFIED INCH SCREW THREADS
TABLE 2 SCREW THREA D GAGES AN D MEA SURIN G EQUIPMEN T FOR
INTERNAL PRODUCT THREAD CHARACTERISTICS (CONT'D)
Thread Gages
and
Measuring Equipment
4.5 Mi ni mu m material
-
itch diameter type- one
and vee
4.6 Mi ni mu m material -thread groo ve diameter
type
-
one only
4.7 Mi no r diameter and pitch diam eter runout gage
4.8 Differentia l segment or ro ll
(GO
profile for one pitch in length)sed in combination
with
a
GO ndica ting gage to yield a diameter equivalent
for variation in lead (in cluding uniform ity o f elix), and
a
minimum material indicating gage to yield
a
diameter
equivalent for variation in flankngle
5 Indicating Plain Diameter Gages
5.1 Maj or diameter type
5.2 Mi no r diameter type
6 Pitch Microme ter With Standard Contacts [Approximately
NOT
GO (HI)
Profile] Cone and Vee
7 Pitch Micro mete r With Modi fied Contacts (Approximately
Pitch Diameter Contact) Cone and Vee
8 Thread-Measuring Balls Wi th Suitable Measu ring Means
9 Optical Comparator and Toolmaker's Microsco pe With
Suitable Fixturing andCast Replica
10
Profile Tracing Equipment With Suitable Fixturing
14Surface MeasuringEquipment
15
Roundness Equipment
Maximum
Material
G O
Func.unc.
limit Size
A l A 2
NOTE:
(1) Minimum major diameter limi t is acceptable when product passes GO gage.
8
Unifi ed Inch Threads
NOT GO
Functional
Diameter
+
I.
-
Minimum Material
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83 m
2 5 7 5 5 3 2 0 0 3 3 b 7 0
2
m
SME
8 3 . 2
A N S V A S M E 61.2-1983
AN AMERICAN NATIONAL STANDARD
GAGES AND GAGING FOR
UNIFIED INCH SCREWTHREADS
TABLE
2
SCREW T HREA D G AGES AN D MEA SURI NG EQ UI PM ENT F O R
INTERNAL PRODUCT THREAD CHA RACTERISTICS (CONT'D)
Taper
of Pitch
Cylinder
Roundness
of
Pitch Cylinder
Oval
180
deg.
Multilobe
120 deg.
lead
Incl.
Helix
Variation
Diam.
Runout
Root Minor
Rad. to Pifch
L M
Surface
Texture
i m i t
H
N
9
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` `
`
`
`
` ` `
`
`
`
`
`
`
`
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10
-
ASME
B3.2 8 3 2 5 7 5 5 3 2
0033673
'4
ANSVASME B1.2-1983
AN AMERICAN NATIONAL STANDARD
2.2.3
Indicating gages for internal threads smaller
than 3 / 16 in. are not available.
2. 3 Determining Size of Gages
2.3.1 Measuring Pitch Diameter. The three-
wire method of determining pitch diameter size of
thread plug gages is standard for gages in this Stan-
dard. Refer to Appendix B.
2.3.2
Size limit adjustments of thread ring and
external thread snap gages are determined by their fit
on their respective calibrated setting plugs. Indicat-
ing gages and hread gages forproduct xternal
threadsare controlled by reference to appropriate
calibrated setting plugs.
2.3.3
Size limit adjustments of internal thread
snap gages are determined by their fit on their respec-
tive calibrated setting rings. Indicating gages and
otheradjustable hread gages for product nternal
threads are controlled by reference to appropriatecal-
ibrated setting rings or by direct measuring methods.
2.4 Standard Temperature
2.4.1
A temperature of 68°F (20°C) is the stan-
dard temperature used internationally for linear mea-
surements. Nominal dimensions of gages and product
as specified and actual dimensions as measured shall
be within specified limits at this temperature. For
screw thread gaging, the acceptable tolerance on the
standard temperature is 3~ 2° F (k 1C).
2.4.2 As product threads are frequently checked
at temperatures which are not controlled, it is de-
sirable that the coefficient of the thermal expansion
of gages be the same as that of the product on which
they are used. Inasmuch as the majority of threaded
product consists of iron or steel, and screw thread
gages are ordinarily made of hardened steel, this
condition is usually fulfilled without special atten-
tion, provided thread gages andproduct have sta-
bilized to the same temperature. When the materials
of the product thread and thegage are dissimilar, the
differing thermal coefficients can cause serious com-
plications and must be taken into account, nless both
product and gage at the time of gaging are at a tem-
perature
of:
a) 68°F k4"F (20°C +2"C) for 1 in. and smaller
6) 68°F k2"F (20°C +l°C) for sizes above 1 in.
to 3 in.
GAGES AND GAGING FOR
UNIFIED INCH
SCREW
THREADS
(C) 68°F +1"F (20°C +0.5"C) for sizes above 3
in. to 6 in.
3 GENERAL PRACTICE
3.1
General Design
The design of gages is specified only to the extent
that it affects the results obtained in the gaging of
product hreads, Moreover, to serve their intended
purposes satisfactorily, thread gages should be pro-
duced by the atestand best manufacturing tech-
niques. The type of steel or wear-resistant material
selected, together with the heat-treating and stabili-
zation processes, should provide wear life and dimen-
sional stability. Thread gaging elements should be
precisely manufactured to assure adequate refine-
ment of surface texture, prevention or elimination of
amorphous or smear metal, and uniformity of thread
form over the entire length of the gaging member.
3.2 Types of Gages
For GO thread gages, check either the maximum-
material limit or size to assure interchangeable assem-
bly. For NOT GO (HI and LO) thread gages, inspect
the NOT
GO
functional diameter limit.
For G O and NOTGO plain cylindrical plug or ring
gages and snap or indicating gages, check the limit or
size of the minor diameter of product internal threads
and the major diameter of product external threads,
respectively.
3.3 Interpretation
of
Tolerances
Tolerances on lead, half-angle, and pitch diameter
are variations which may be taken independently for
each of these elements and may be taken to the extent
allowed by respective tabulated dimensional limits.
The tabulated tolerance on any oneelement must not
be exceeded, even though variations in the other two
elements are smaller than he respective tabulated
tolerances.
3.4
Direction o f Tolerances on Gages
At the maximum-material limit (GO), the dimen-
sions of all gages used for final conformance gaging
are to e within the limits of size of the product thread.
At the functional diameter limit, using NOT
G O (HI
and LO) thread gages, the standard practice is to have
the gage tolerance within the limits ofsize of the
product thread, Specifications for gage limits are listed
in Tables 4 and 5.
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ASME B 3 - 2
83
m
2 5 7 5 5 3 2 0031672 b
GAGES'AND
GAGING
FOR
UNIFIED NCHSCREWTHREADS
3.5 Standard Thread Gage To-lerances
Standard tolerances for thread-working gages,
thread-setting plugs, and setting rings are as follows:
( a )
W tolerance, shown in Table 7, represent the
highest commercial grade of accuracy and workman-
ship and are specified for thread-setting gages;
b)
X tolerances, shown in Table 6, are larger than
W tolerances andare used forproduct inspection
gages.
Unless otherwise specified, all thread ages and gaging
contacts which directly check the product threadhall
be X tolerance.
3.6
Tolerance on Lead
Cumulative effect of progressive or erratic helix
variation and thick or thin end thread Variations is
specified as an allowable variation between any two
threads not farther apart than the length of the stan-
dard taperlock or trilock gage, shown in ANSIB47.1.
In the case of setting plugs, the specified tolerance
shall be applicable to the thread length in the mating
ring gage or nine pitches, whichever is smaller. For
setting rings, the tolerance applies to a thread length
of three pitches. The tolerance on lead establishes the
width of a zone, measured parallel to the axis of the
thread, within which the actual helical path must lie
for the specified length of the thread. Measurements
will be taken from
a
fixed reference point located at
the start of the first ull thread to a sufficient number
of positions along the entire helix to detect all types
of lead variations. Th e amounts that these positions
vary from their basic (theoretical) positions will be
recorded with due respect to sign. The greatest varia-
tion in each direction [plus and minus
(*)I
will be
selected and he sum of their values, disregarding
sign, shall not exceed the specified tolerance. If the
variations are all in one direction, the maximum value
governs conformance. In the case of truncated set-
ting plugs, the lead variations present on the full-
form portionand the truncated portion of an individ-
ual gage shall notdiffer from each other by more than
0.0001 in. over any portion equivalent to the length
of the thread ring gage, or nine pitches, whichever is
less. (When linear lead and drunkenness are measured
as individual elements and the sum of these does not
exceed the tolerance specified, the gage is well within
tolerance.)
3.7 Tolerances
on
Half-Angle
Tolerances are specified for the half-angles rather
than the included angle to assure that the bisector of
the included angle will be perpendicular to the axis
11
ANSVÄSME B1.2-1983
ANAMERICANNATIONALSTANDARD
of the thread within proper limits. The equivalent of
the variation romthe true thread form caused by such
irregularities
as
convex, concave or wavy flanks,
rounded crests, or slight projections on he thread
formshallnot exceed the tolerance permitted on
half-angle.
3.8
Check of Effect of Lead and Flank Angle
Variations on Produc t Thread
When this check is specified, there are two general
methods available forhe inspection procedures
involved.
(a) Direct Measurement
of
Lead and Half-Angleof
Flanks. The lead and flank angles of theproduct
thread may be measured by means of available mea-
suring equipment, such as thread indicating gages,
projection comparators, measuring microscopes,
graduatedcone points, lead measuring machines,
helix variation measuring machines, thread lank
charting equipment, etc. Diameter equivalents of such
variations from nominal maybe calculated: each
0.0001
in. variation in lead amounts to 0.00017 n.
(1.732 X .OOOOl) increase in functional pitch diameter
on external threads or a decrease in functional pitch
diameter on internal hreads for 60 deg. screwhreads.
The tangent of half-angle variation times 1 . 5 ~quals
the approximatemaximum change in functional pitch
diameter, based on a height of thread engagement of
0.6258 and equal half-angle variations.
b) Differential Gaging Utilizing Indicating Thread
Gages.
See Sections 4 and 5 for explanation and il-
lustration of differential gaging for internal and ex-
ternal threads.
3.9
Calibration Requirements and Standards
Calibration requirements and standards for X tol-
erance thread gages, snap gages, and indicating gages;
Z
tolerance plain gages and measuring instruments
are given in Table 12 for external product threads,
in Table13 for internal product threads, and in Table
14 for setting gages. See Appendix A for methods of
calibrating and inspecting gages.
4
TYPES OFGAGES FOR PRODUCT
INTERNAL THREAD
4.1 GO Working Thread Plug Gages
(Table
2-
Gage 1
.I
4.1
.I PurposeandUse. The
GO
thread plug
gage inspects the maximum-material GO functional
limit, A l , of product internal thread. The GO thread
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ASME
B3.2 8 3 m 2 5 7 5 5 3 2 0 0 3 3 b 7 3 8 m
ANSL'ASME
BI
.2-1983
AN A MERICAN NATIONAL STANDARD
GAGES AND GA GING
FOR
UNIFIED INC H SCREW THREADS
FIG. 1 MAXIMUM-MATERIAL GO FUNCTIONAL LIMIT
gage represents the maximum-material GO functional
limit
of
the product internal thread, and its purpose is
to assure interchangeable assembly of maximum-
material mating parts. GO thread pluggages must
enter and pass through the full-threaded length of the
product freely. The GO thread plug gage isa cumula-
tive check of all thread elements except the minor
diameter.
4.1.2 Basic Design. The maximum-material
limit on GO thread plus gages s made to the pre-
scribed maximum-material limit of the product in-
ternal thread, and the gaging length is equal to the
length of the gaging plug.
4.1.3 Gage Blanks. For practical and economi-
cal reasons, the design and lengths of the gaging plug
members have been standardized for various size
ranges and pitches (see ANSI
B47.1
or Table A3).
4. 1. 4 Thread Form. The specifications for
thread form are summarized in Table 4 and Fig. 1 .
4.1.5 Thread Crests.
The major diameter of the
GO thread plug gage shall be the same as the mini-
mum major diameter of the product internal thread
with a plus gage tolerance. The thread crests shall be
flat in an axial section and parallel to the axis.
4.1.6 Thread Roots. The minor diameter of the
GO thread plug gage shall be cleared beyond
a
p / 8
width of flat either by an extension
of
the sides of
the thread toward a sharp vee or by an undercut no
greater than
P/
maximum width and approximately
central.
4.1.7 Runout of Pitch and Major Cylinders.
On thread plug gages an eccentric condition produces
an oversize effective major diameter having a width
of flat less th an p/ 8, which may encroach on the min-
imum permissibIe imit for heroot profile of the
product internal thread. The permissible maximum
effective major diameter, as determined by adding
measurement of runout (full-indicator movement)
with respect to he pitch cylinder to he measured
12
,
fl
\,
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- A S M E
B I - 2
8 3
2 5 7 5 5 1 2 0 0 1 1 b 7 4 T =
~
GAGES AND GAGING FOR
UNIFIED NCHSCREWTHREADS
major diameter, shall not exceed the maximum major
diameter specified.
4.1.8
Pitch Cylinder. The pitch cylinder shall be
round and straight within the gage pitch diameter
limits specified.
4.1.9
eadand Half-Angle Variation s. Lead
and half-angle variations shall be within the limits
specified. See Table 6.
4.1
IO incom plete Thread.
The feather -edge
at both ends of the threaded section of the gaging
member shall be removed. On pitches coarser than 28
threadslin., not more than one complete turn of the
end threads shall be removed to obtain a full-thread
form blunt start.See Fig. 2. On pitches 28 threadsl in.
and finer,
a
60 deg. chamfer from the axis of the gage
is
acceptable in lieu of the blunt start.
4.1
I 1 Chip Grooves.
Each
GO
thread plug
gage, except in sizes No. 8 (0.164in.) and smaller, shall
be provided with
a
chip groove at the entering end. On
reversible gages, a chip groove shall be provided at
each end. Chip grooves that are in accordance with
commercial practice are acceptable, such as a groove
cut at an ngle with the axis or a longitudinal groove
cut parallel with the axis and extending the complete
length of the gaging member. The groove shall be lo-
cated circumferentially at the start f the full thread,
and in all cases the depth shall xtend below the root
of the first full thread. The distance from the major
diameter of the thread plug to the crest of the con-
volution rise in front of the chip groove, due to the
radius of the convoluting tool, shall be a minimum of
H / 2 as shown in Fig.
2.
The beginning of the first
thread shall be full form. The recommended widths
for chip grooves are as shown in Table 3.
4.1.1
dentification. The
GO
thread plugs
should be identified by the nominal size, threadslin.,
thread series, GO,
PD,
and pitch diameter.
EXAMPLE:
k .
1/4-20
(or
.250-20) UNC G O PD.2175
4.2NOT GO (Hi) Thread Plug Gages
(Table
2
- Gage
1.2)
4.2.1
PurposeandUse. TheNOT GO (HI)
thread plug gage inspects the NOT
GO
(HI)
func-
tional diameter limit, B I ,of product internal thread.
The NOT
G O
(HI) thread plug gage represents the
13
ANSI/ASME B 1 2 - 1 983
ANAMERICANNATIONALSTANDARD
TABLE 3 RECO M MENDE D W I DT HS
F O R CHI P G RO O VES
Chip Groove
Width, in.
Nominal
Diameter,
in.
M a x .
Min.
No.
8 0.164) and smaller No chip
groove
required
Above No. 8 0.164) to
and
including
No. 12 (0.216).036.026
Above
No.
12 (0.216)
to
and including
3/8 (0.375).052.042
Above 3/8 (0.375) to and including
1/2 (0.500)
0.067.057
Above 1/2(0.500)
to
and including
1
(1.000)
0.083
0.067
Above 1 (1.000) to and including1-3/4 (1.750)
0.130.067
Above 1-3/4 (1.750)
0.193.067
NOT GO (HI) functional diameter limit of the prod-
uct internal thread.
Thread plug gages when applied to the product in-
ternal thread may engage only he end threads (which
may not be representative of the complete thread).
Entering threads on product are incomplete and per-
mit gage to start. Starting threads on NOT
GO (HI)
plugs are subject to greater wear than the remaining
threads. Such wear in combination with the incom-
plete product hreads permits furtherentry
of
the
gage. NOT
GO (HI)
functional diameter isaccep-
table when the NOTGO (HI) thread plug gage pplied
to the product internal thread does not enter more
than three complete turns. The gage should not be
forced, Special requirements such as exceptionally
thin or ductile material, small number of threads, etc.,
may necessitate modification of this practice.
4.2.2
asic Design. To better check the maxi-
mum functional diameter limit, the flank contact is
reduced by truncating the major diameter, and the
length of the gaging element, where practica1,'is less
than that of the
GO
gage.
4.2.3'
age Bianks.
For practical and ecqnomic
reasons, the designs and lengths of the gaging ele-
ments have been standardized for various size ranges
and pitches (see ANSI B47.1 or Table A3).
4.2.4
hread Form. The specifications or thread
form are summarized in Table 4 and Fig.
3.
4.2.5
hread Crests. The maximum major di-
ameter of the NOT
GO (HI)
thread plug gage shall
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A N S V A S M E B1.2-1983
AN AMERICAN NATIONAL STANDARD
GAGES AND GAG ING FOR
UNIFIED INCH SCREW THREADS
Gr ind ing wheel o r
convo lu t i ng too l
,
'.
Remove inco mp lete thread
fo r one com ple te tu rn a t
bo th ends.
FIG.
2
PARTIAL
END
THREA DS AND CHtP GROOVES
be equal to the maximum pitch diameter of the prod-
uct internal thread plus 0 .5H with the gage tolerance
minus. This corresponds to a width of flat at the
crest of the gage equal to
0.25~.
ee Table
4.
4. 2. 6 Thread Roots.
The minor diameter of the
NOT GO (HI) thread plug gage shall be cleared be-
yond a
p/8
width of -flat by
an
extension toward a
sharp vee of the sides of the thread from theposition
corresponding to this approximate width; or by an
undercut to any dimension no wider than the width
resulting from
p/8
maximum width, either side of
and approximately central with the center line of the
thread groove.
4.2.7
Runout
of
Pitch and Major Cylinders.
The permissible maximum effective diameter, as de-
termined by adding measurements
of
runout (full-
indicator movement) with respect to the pitch cylinder
to the measured major diameter, shall not exceed the
maximum major diameter specified,
4.2.8 Pitch Cylinder.
The pitch cylinder shall
be round and straight within the gage pitch diameter
limits specified.
4.2.9 Lead and Half-Angle Variations. Lead
and half-angle variations shall be within the limits
specified. See Table
6 .
4.2.10 Incomplete Thread. The feather edge at
both ends of the threaded section of the gaging mem-
ber shall be removed. On pitches coarser than
28
threadslin., not more than one complete turn of the
end threads shall be removed to obtain a full-thread
blunt start. See Fig.
2.
On pitches
28
threadslin. and
finer, a 60 deg. chamfer from the axis of the gage is
acceptable in lieu of the blunt start.
4.2.1 1
Identification.
The NOTGO H1)thread
plug gage should be marked with the nominal size,
threadslin., thread series, class, NOT GO,
PD,
and
pitch diameter.
EXAMPLE:
1/4-20 (or .250-20) UNC-2B NO T GO PD.2224
4.3
Thread Snap Gages -
GO
Segments or
Rolls (Table 2 - Gages 2.1 and 2.3)
4.3.1 Purpose and Use.
The hreadsnap gage
with two G O threaded segments or two GO zero lead
14
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ASME B I - 2
83
2 5 7 5 5 3 2 00LLb7b 3
GAGESANDGAGINGFOR
UNIFIED NCHSCREWTHREADS
ANSI/ASME BI .2-1983
AN AMERICANNATIONALSTANDARD
TABLE
4
SPECIFICATIONS A ND FO RM A T F OR TABLES 10 A N D 11- IMITS OF SIZE O F THREADED
A ND PL A IN GAGES FOR UNIFIED EXTERNAL A N D INTERNAL THREADS
Nominal
Size
and Threadslin.
1
Series Designation and Tolerance Class
2
~~
Gages for
External
Threads
Gages for
Internal
Threads
Thread gages
Plain gages
for major
diameter
Thread gages
Plain gages
for minor
diameter
CO
Pitch
diameter l
I
Minor
diameter l 4
Pitch
NOTGO(LO)
Minor
diameter
;
OT
GO
GO
NOT GO HI )
Major
9
diameter
Pitch
10
diameter
Major
11
diameter
Pitch
12
diameter
q
OT GO
Series Designation and Tolerance Class
15
(To be specified)
Of external thread to be checked
Max. pitch diameter of external thread;
gage tolerance minus
M a x . pitch diameterof external hread;
minus H/2; gage tolerance minus
Min. pitch diameter of external thread;
gage tolerance plus
Min. pitchdiameter of external thread
minus 0.25H; gage tolerance plus
Max.
major diameter of external
thread; gage tolerance minus
Min. major diameter of external
thread; gage tolerance plus
Min. major diameter of internal
thread; gage tolerance plus
Min. pitch diameter
of
internal thread;
gage tolerance plus
Max. pitch diameter of internal thread
plus H/2; gage tolerance minus
Max. pitch diameter of internal thread;
gage tolerance minus
Min. minor diameter of internal
thread; gage tolerance plus
M a x . minor diameter of internal
thread; gage toLerance minus
Of internal thread to be checked
rolls inspects the maximum-material
GO
functional
limit, A l , of product internal thread, The setting of
the
GO
segments or rolls represents the maximum-
material
GO
functional limit of the product internal
thread, and its purpose is to assure interchangeable
assembly of maximum-material mating parts.The
segments or rolls theoretically engage over the full-
threaded length of the product. The segments or rolls
have a cumulative check
of
all thread elements except
the minor diameter.
Internal thread snap gages by design must have an
outside diameter of gaging elements below minor
diameter of internal thread in ordero enter. Thegage
checks all thread elements by sensing the resistance
of contact after being set to a master.
15
The GO thread snap gage can also indicate out-of-
roundness of pitch cylinder for
180
deg. ovality by us-
ing the gage at different internal diametral locations
on the product thread.
4.3.2
Basic
Design.
The
GO
segments and rolls
assembled into gage frames are the design of the in-
dividual gage manufacturer. The lengths of the two
threaded segments and he two thread rolls spaced
180 deg. apart are equivalent to the standard gage
blank lengths for practical and economic reasons. Se e.
Table A3 and Fig. 4. Internal product threadsess than
3/16 in, in diameter are not practical to check with
snap gages. GO thread segments shall engage
25
or
more of the product circumference. Product shall 'be
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ASME B I - 2 83 U 2 5 9 5 5 1 2 0011678
7
GAGES AND GAGING FOR
UNIFIED INCH SCREW THREADS
ANSI/ASME
61.2-1983
AN AMERICAN NATIONAL STANDARD
TABLE
5
S PE CIF ICA TIONS A N D FOR MA T FORTABLES
10
A N D 11
-
IMITS
OF
SIZE O F THREAD-
SETTING GAGES FOR UNIFIE D THR EA D WO RK ING AGES
1
2
-
(To
be specified)
Of external thread to be checked byage set
with plug
Max. majordiam. of external threadequals min.
major diam. of full portio n of GO etting plug)
minus (0.060
G+
.017~);gage tolerance
minus
Max. major diameter of external hread;
gage tolerance plus
Max. pitch diameter of external thread;
gage tolerance minus
Min.
pitch diameter of external thread plus
/ 2 ;
gage tolerance minus
Max. major diameter f external thread provided
major diametercrest width shall not beess than
0.001 in. (0.0009 in. truncation). Apply W
tolerance plus for max. size except that for
0.001 n. crestwidth apply toleranceminus.
For the 0.001 in. crest width, major diameter
is
equal to maximum major diameter
f
external
thread plus 0.216506~ minus theum of
external thread pitch diameter tolerance and
0.0017 in.
Min. pitch diameter of external thread;
gage tolerance plus
Min.
pitch diameter of internal thread;
W gage tolerance plus
Min. minor diameter of internal thread;
W
gage tolerance minus
M a x . pitch diameter of internal thread;
W gage tolerance minus
Max. minor diameter of internal thread;
W gage tolerance minus
Of internal thread o be checked byage set
with ring
Nominal Size and Threaddin.
Series Designation and ToleranceClass
3
Truncated
Major
diameter
lug for GO
Full-form
4
-
5itch diameter
Truncated*
(Note 1)
6
ull-Form
and
Truncated
Setting
Plugs
Full-form
ajor
diameter
7
Plug for
N O T
GO
(LO)
8
9
Pitch diameter
Pitch diameter
(Note 2)
Ring for
GO
Mino r diameter 10
-
11
Solid Thread-SettingRings for
Snap and Indicating Gages
Pitch diameter
(Note 2)ing for
NOT GO
(HI)
12
-
13
Min or diameter
Series Designation and ToleranceClass
*
Indicated rows applyo truncated sefting plugs only.
NOTES:
(1) Truncated portion
s
required when optionalsharp root profile
n
Figs. 18,19,20,21, and 26 s used.
(2) Tolerances greater than
W
tolerance for pitch diameter are acceptable when infernal indicatingr snap gage can accomodate a
greater tolerance and whenagreed upon bysupplier and user.
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A S M E 8 3 . 2 8 3 m 2 5 7 5 5 3 2 0 1 3 6 7 7 7
A N S V A S M E B1.2-1983
AN AMERICAN NATIONAL STANDARD
GAGES AND GAG ING FOR
UNIFIED INCH SCREW THREADS
TABLE
6
X
GAGE TOLERANCES FOR THREAD GAGES
Threads/in.
1
80
72
64
56
48
44
40
36
32
28
27
24
20
18
16
14
13
12
11%
11
10
9
8
7
6
5
4%
4
Tolerance
on Lead, n.
(Notes 1, 3)
2
0.0002
.0002
.0002
.0002
.0002
.0002
,0002
.0002
.0003
.0003
.0003
.0003
,0003
.0003
.0003
.0003
.0003
.0003
.0003
.0003
.0003
.0003
.0004
.0004
.0004
.0004
.0004
.0004
Tolerance on
Half-Angle
of Thread,
deg. k min.
3
0 30
0 30
0 30
0 30
0 30
0 20
0 20
0 20
0 15
0 15
0 15
0 15
0 75
0
10
0 10
0 10
0 10
0
10
0
IO
0 10
0 10
0
10
0 5
0 5
0 5
0 5
0 5
0 5
Tolerance on Major
or Minor Diameters
(Note 4)
To and
Including
4 in. Diam.
4 -
0.0003
.0003
.0004
.0004